C23000 Red Brass Tube: The 85/15 Alloy and Its Designations
C23000 red brass tube contains about 85 % copper and 15 % zinc and is the standard 85/15 red brass of the copper tube trade. It is also identified as EN CuZn15, DIN CEN/TS 13388 CW502L, BS CZ102, JIS C2300 and GB/T 5231 H85. The higher copper content compared with 70/30 brass gives better corrosion resistance and a deeper red colour, while retaining enough zinc to keep the alloy economical and free machining.
Seamless tube in this grade is ordered to ASTM B135, ASTM B43/B43M and ASTM B587 with the corresponding ASME SB135, SB43 and SB587 specifications, or to JIS H3250 when a Japanese equivalent is wanted. The alloy is ductile enough for cold drawing and bending, which is what makes thin walled tube down to 0.25 mm wall thickness practical without cracking.
Composition and Mechanical Properties
| Element | Cu | Fe | Pb | Zn |
|---|---|---|---|---|
| Min / Max, % | 84.0 - 86.0 | 0.05 max | 0.05 max | balance |
| Nominal, % | 85.0 | - | - | 15.0 |
Tube is supplied in the soft annealed and cold-drawn tempers. Tensile strength runs from roughly 274 MPa in the soft condition to 414 MPa and above in the harder drawn tempers, so the material can either be formed and bent on site or used as a stiff, self-supporting tube without extra support. Yield strength, elongation and hardness follow the temper table of the applicable specification, and the manufacturer's certificate states the actual values for the delivered lot. Ductility remains high enough in the annealed condition to permit tight radius bending, flaring and double flaring for flare fittings.
The alloy combines high thermal and electrical conductivity with useful strength, characteristics that explain its use in heat transfer and electrical hardware as well as in fluid systems. Its resistance to dezincification and to stress corrosion cracking in ordinary service environments is the main reason it is selected for fittings and tube exposed to water and weather for decades.
Thin Wall Tube Range and Applications
Outside diameter is offered from about 4 mm to 150 mm and wall thickness from 0.25 mm to 8 mm, in round, square, rectangular and hydraulic forms, with lengths of 1 m, 2 m, 3 m, 4 m and 6 m plus single random, double random and cut-to-length supply. Thin wall tube is coiled or supplied straight in fixed lengths depending on diameter and wall.
Plumbing and sanitary tube, water distribution and brass plumbing goods.
Heat exchanger, condenser and radiator tube, including ferrule and U-bend stock.
Marine and offshore hardware where humid or salt-bearing atmospheres are present.
Architectural tube for trim, railing and decorative framing.
Electrical and instrument components that need conductivity together with strength.
Fabrication Notes, Inspection and Delivery
C23000 cold forms well, brazes and solders easily and can be welded by the usual fusion processes, although brazing is the more common production route for tube assemblies. Bending should be carried out in the annealed or lightly drawn temper, and the bend radius should be kept generous when the wall is thin. Where tube is expanded into tube sheets, the annealed temper gives the most reliable joint.
Every lot is checked by spectrometer for chemical composition and by tensile and hardness testing for mechanical values. Tube is gauged for outside diameter, wall thickness and length, inspected for internal and external surface condition, and can be eddy current tested or pressure tested when specified. Packing is arranged for sea, air and courier shipment with plastic film, wooden cases or steel-strapped bundles, and mill test certificates are issued for each heat. Straightness, ovality and burr-free ends are controlled when tube is destined for automatic assembly lines.
Frequently Asked Questions
Q: What is C23000 red brass tube made of?
A: It is an 85/15 copper-zinc alloy with 84.0 - 86.0 % copper, a maximum of 0.05 % iron and 0.05 % lead, and zinc as the balance. It is the same alloy as CuZn15, CW502L, CZ102, C2300 and H85.
Q: Which specification applies to C23000 seamless tube?
A: ASTM B135 and ASME SB135 are the usual tube references, with ASTM B43/B43M for standard size pipe and ASTM B587 for welded tube. JIS H3250 covers the Japanese equivalent.
Q: How thin can the wall be?
A: Thin walled seamless tube is regularly produced with wall thickness from 0.25 mm upward, with outside diameter from about 4 mm to 150 mm, depending on the drawing limits of the required temper.
Q: Is 85/15 red brass better than 70/30 brass for water service?
A: The higher copper content of C23000 gives better corrosion resistance and dezincification resistance than the lower copper brasses, which is why it is preferred for water, sanitary and marine tube work.
Q: What temper should be ordered for bending?
A: Soft annealed temper is used where tight radius bends, flaring or flanging are required, while half hard and harder tempers are selected for straight runs and for parts that must hold their shape.
Q: Are mill test certificates provided?
A: Yes. Each heat is supplied with a mill test certificate showing chemical analysis and mechanical properties, and dimensional or pressure test records can be added when the order requires them.
